Question

write an activity with labelled diagram to show convection current during heating of water by using potassium permagnate.​

Answer 1

Materials:

• 200 ml glass beaker
• potassium permanganate
• Bunsen or spirit burner, tripod stand, wire gauze

Instructions:

1. Half fill the beaker with cold tap water.
2. Carefully put a small amount of potassium permanganate on one side of the beaker. DO NOT STIR.
3. Heat the water directly under the side of the beaker with potassium permanganate with a Bunsen/spirit burner and observe what happens.
4. Set up a control experiment and place a few grains of potassium permanganate into the bottom of a beaker filled with water. Do not heat this beaker and observe what happens.

Observation:

• Convection is the transfer of thermal energy from one place to another by the movement of gas or liquid particles.
• As a gas or liquid is heated, the substance expands. This is because the particles in liquids and gases gain kinetic energy when they are heated and start to move faster. They therefore take up more space as the particles move further apart. This causes the heated liquid or gas to move upwards and the colder liquid or gas moves downwards. When the warm liquid or gas reaches the top it cools down again and therefore moves back down again.
• In this activity, the water particles gained kinetic energy and moved apart from each other, therefore taking up more space. This water then moves upwards as it is less dense than the cold water, meaning it it lighter than the cold water. We were able to observe this as the potassium permanganate dissolved in the water and moved with the water particles, and then moved downwards again as the water cooled.
• This movement of liquid or gas, is called a convection current, and energy is transferred from one area in the liquid or gas to another. Have a look at the diagram which shows a convection current.

Answer 2

Explanation:

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